Skim vs SumatraPDF (2026): which should you pick?
As of Nov 13, 2026, Skim and SumatraPDF share a 2.8 GPA, both are free, so the choice depends on whether you care more about features, where Skim grades higher, or platforms, where SumatraPDF does.
Checked Nov 13, 2026 · graded Nov 13, 2026 by ToolGPA
They get the same grade on value for money, the free plan and ease of use.
Price, platforms and features side by side. The table says where each price was read and when.
Which one is for you
Pick Skim if
- Fits if you read and mark up papers on a Mac, especially with LaTeX or BibDesk
- Works for anyone who wants a free annotator and not an editor
Look elsewhere if
- Skip it if you use Windows, Linux or a phone, as it runs on Mac only
- Too light for editing text or filling in forms, since neither is listed
- Watch out: support is a wiki, mailing lists and bug trackers, not a help desk
- Tight if your Mac is old, because the current version needs macOS 10.13
Pick SumatraPDF if
- Fits if you want a light Windows viewer for PDFs, ebooks and comics
- Works for people who keep a portable reader on a USB stick
Look elsewhere if
- Too light for editing, as the pages list no way to change text or pages
- Skip it if you use a Mac or Linux, since the FAQ says there is no version for them
- Not for you if you want phone apps, as none is listed
- Watch out: support is a GitHub discussions forum and documentation, not a help desk
How we grade them
| 2.8GPASkimGood | 2.8GPASumatraPDFGood | |
|---|---|---|
| Value for money | AFree to download and use, with no paid tier, so it sits well under the cheapest quarter of PDF tools. | AFree and open source, with no ads or bundled software, and anyone can download and run it. |
| Free plan and trial | AThe whole app is free, with nothing held back. | AThe whole app is free to download and use, with nothing held back. |
| Features | CNotes, highlights, snapshots, a reading bar and AppleScript. It does that job fully, but it is a smaller one: the listing shows no text editing or form filling. | DIt opens many document formats but the pages list no editing, so for a PDF editing category it covers one narrow function, viewing. |
| Ease of use | BNo store rating is on record, but it is a program you install and open, with nothing to set up. | BNo store rating is on record, but you install or unzip it and open a file, with nothing to set up. |
| Platforms and integrations | DmacOS only, version 1.7.19 needing macOS 10.13 or higher. There is no Windows, phone or web version. | CA Windows desktop app in 32-bit, 64-bit and ARM64 builds, plus a browser version. There is no Mac, Linux or phone app. |
| Best for | reading and annotating papers on a Mac | opening PDFs and ebooks quickly on Windows |
The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: Skim and SumatraPDF. How we grade
Price against what you get
Skim has no paid plan and scores 2.0 out of 4 on features, ease of use and platforms. SumatraPDF has no paid plan and scores 2.0.
On this chart the two sit in the same place: the same score for the same starting price. Of the other PDF editors on the chart, none scores higher than Skim for less, and none scores higher than SumatraPDF for less.
Features, ease of use and platforms, averaged
What paid plans start at, a month (each step along is roughly double) →
- The best score at each price
- Has a free plan
- No free plan
Where they differ
- Skim also covers notes, highlights and pDF editing.
- SumatraPDF also covers documents.
At a glance
| Skim | SumatraPDF | |
|---|---|---|
| Pricing | Free | Free |
| Starts at | Free | Free |
| Free plan | Everything: the whole app is free to download and use. | Everything: the app is free and open source, with no ads or bundled software. |
| Free trial | None listed | None listed |
| Web | ||
| macOS | ||
| Windows | ||
| Made by | Skim project (SourceForge) | Krzysztof Kowalczyk |
| Price read from | skim-app.sourceforge.io | sumatrapdfreader.org |
| Checked | Nov 13, 2026 | Nov 13, 2026 |
Worth knowing
Skim
- Mac only; current version 1.7.19 needs macOS 10.13 or higher, with older versions listed for older systems.
- It is a reader and annotator, with no listed tools for editing existing text or filling in forms.
- Support runs through a wiki, mailing lists and bug trackers rather than a company help desk.
SumatraPDF
- Windows only for the desktop app; the FAQ says there is no Mac or Linux version.
- The home page presents it as a reader; the pages read do not list editing features such as changing text or pages.
- Support is through a GitHub discussions forum and documentation.
Key features
Skim
- Notes and highlights
- Add and edit notes, highlight text with one-swipe modes, and view all notes and highlights in one list.
- Snapshots and reading bar
- Keep snapshots of other parts of a document for reference and focus a line at a time with a reading bar.
- Navigation
- Move around with the table of contents or thumbnails, with a visual history and previews of internal links.
- Presentations
- Present a PDF full screen with built-in transitions, and crop pages with the smart cropping tools.
- Export and scripting
- Export notes as text and automate with extensive AppleScript support.
- LaTeX and reference tools
- Works with LaTeX through SyncTeX and PDFSync, and integrates with BibDesk and other third-party apps.
SumatraPDF
- Many document formats
- Opens PDF, EPUB, MOBI, CBZ and CBR comics, DjVu, XPS, CHM and common image formats, including JPEG XL and HEIC.
- Light and fast
- The site describes an app that opens documents instantly with minimal memory use.
- Portable option
- Can run without installation, for example from a USB drive.
- Customization
- Keyboard shortcuts, themes and the toolbar layout can be changed.
- Windows builds
- Native 32-bit, 64-bit and ARM64 builds for Windows 7, 8, 10 and 11.
- Web version
- A browser version is linked from the site's main navigation at web.sumatrapdfreader.org.
Plans
Skim
Skim$0
Free to download; the site lists no paid plans or licence fees.
SumatraPDF
Free$0
Free and open source, with no ads, bundled software or subscription.
Common questions
Which is cheaper, Skim or SumatraPDF?
As of Nov 13, 2026, both Skim and SumatraPDF are free to use.
Which has a free plan, Skim or SumatraPDF?
As of Nov 13, 2026, both Skim and SumatraPDF have a free plan.
Which platforms do Skim and SumatraPDF run on?
As of Nov 13, 2026, only Skim lists a macOS app and only SumatraPDF lists a web app and a Windows app. A platform missing from a listing is one its maker's pages did not mention.
More comparisons
How this page was made
- The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
- The grades are our own, from each tool’s review or report card. The GPA is their average.
- Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
- The differences and the answers to the questions are worked out from those listings.